Respiratory disease is a common and frequently-occurring disease, which has the main pathologenic changes in trachea, bronchi, lung and pleural cavity. Mild patients generally have cough, chest pain, and have breathing disturbed, while severe patients have difficulty in breathing, have hypoxia, or even die due to respiratory failure.
Since the 21st century, with the rapid development of economics and constantly accelerating process of urbanization in China, air pollution has become an inevitable practical issue. The respiratory problems caused thereby have drawn global attention. According to a large number of epidemiological surveys and statistics, respiratory disease (not including lung cancer) accounted for 13.1% of death in urban residents (ranking fourth among various causes of death) and 16.4% in rural residents (ranking third among various causes of death).
Airway inflammatory disease, which is one of the common and frequently-occurring respiratory diseases in clinic, refers to inflammatory disease in upper airway (mainly including nose, pharynx and larynx) and lower airway (mainly including trachea). It is characterized by airway inflammation and tissue remodeling, and is manifested as changes in epithelial cells, mucosal and submucosal exudation and infiltration of inflammatory cell, hypertrophy and hyperplasia of goblet cells, strong glandular secretion, subepithelial edema, basement membrane thickening and fibrosis, etc. Its pathogenic cause is mainly associated with smoking, air pollution, infection, harmful gas, dust inhalation, and intrinsic factor of organism, etc. For site of the organism in direct contact with inhalation irritants, symbionts, and pathogens, airway barrier protection is weakened, which stimulates the participation of active oxygen system, various inflammatory cell and inflammatory mediators, thereby aggravating the inflammatory response. Therefore, the treatment against inflammation has become the most critical part in the treatment of airway inflammatory disease.
Chronic obstructive pulmonary disease (COPD) is a chronic, refractory, senile respiratory disease, characterized by incompletely reversible airflow limitation, and has a high disability rate and mortality. Many inflammatory cells such as neutrophils, alveolar macrophages and lymphocytes promote the occurrence and development of chronic airway inflammation in different phases by releasing various bioactive substances such as interleukin, tumor necrosis factor and so on. Airway mucus hypersecretion and inflammatory response, considered as one of the important causes for COPD, eventually lead to airway obstruction and airflow limitation.
Bronchial asthma is a common respiratory disease in adults and children, and its pathological characteristic is chronic airway inflammation in which various inflammatory cells are involved, such as eosinophils, lymphocytes, mast cells and neutrophils.
Pulmonary fibrosis, particularly idiopathic pulmonary fibrosis, has been considered for a long time as a progressive and substantially irreversible pathological change. That is, it starts from infiltration of inflammatory cell in lower respiratory tract, gradually leads to injury to alveolar epithelial cells and vascular endothelial cells, is accompanied by the release of cytokines and the like which can promote proliferation of myofibroblasts and alveolar type II epithelial cells, results in extracellular matrix protein and collagen deposition, and finally causes damage to lung structure.
Therefore, how to effectively treat respiratory disease has become a problem to be solved urgently.
There are documents showing that about 80% of drugs available in market are derived from natural products directly or indirectly, and natural drugs have become an important source for the development of therapeutic drugs for human. However, it has not been reported yet that natural drugs have a significant inhibitory effect on respiratory disease.
Alstoniascholaris (L.) R. Br., also called Alstonia scholaris, is a plant of the genus Alstonia of the family Apocynaceae. Its medicinal parts are root, bark and leaf. Alstonia scholaris contains various alkaloids having relatively high bioactivities, such as picrinine, vallesamine, scholaricine and 19-epischolaricine.
The structure of picrinine is as follows:

The structure of vallesamine is as follows:

The structure of scholaricine is as follows:

The structure of 19-epischolaricine is as follows:

Alstonia scholaris is generally used for the treatment of headache, pneumonia, pertussis, and chronic bronchitis in civilian populations. It has been recorded in the local journal of medicine such as “Lu Chuan Ben Cao”, “Selections of Chinese herbal medicines of Yunnan” and “Drug Standards of Yunnan Province” (1974) and “Pharmacopoeia of the People's Republic of China, Vol. 1” (published in 1977). Leaves of Alstonia scholaris can clear internal heat, remove phlegm and relieve a cough, and are useful for cough resulted from pulmonary retention of phlegmopyrexia, stethocatharsis, and chronic bronchitis, as well as pertussis having the above-mentioned syndromes. It has not been reported yet that Alstonia scholaris has a significant inhibitory effect on respiratory disease.